I have a raptor 30 heli that i have a sanyo 4.8v 1100MaH battery in and i couldnt get the charge to last more than about a day it would be almost completly dead. they do get a memory, i have charged it up and just left the switch on while im at work to completly dishcarge it as i do not have a good charger yet. then when i got home i would recharge it and then monitor how much it drops 12 hrs after disconnecting it. well after about 3 complete drains and recharges it seems to be working optimally again. I would drain them completly dead and recharge a couple times they should get better but some discharge is normal.